This application claims priority from German Patent No. DE 100 13 213.8 filed on Mar. 17, 2000, which is incorporated herein in its entirety.
The invention relates to a system for picking articles situated on retrieval pallets or in special containers in rack storage units.
The object of the invention is substantially to provide a system of a kind which is notable primarily for combining extreme flexibility and high efficiency with optimum ergonomics.
Said object is achieved substantially by a system of the type described initially, comprising: 1) a plurality of parallel rack rows for the storage and intermediate storage of units for receiving the articles, 2) storage aisles and picking aisles formed alternately between the rack rows, 3) at least one storage vehicle in each storage aisle, which vehicle is designed to receive at least one unit and is capable of traveling along each storage aisle to place the units into storage in the pallet racks, 4) at least one picker vehicle which in each picking aisle, for picking the articles to be picked, is capable of traveling along in each case one of the two mutually opposing picking fronts forming the picking aisle, 5) buffer locations, which are disposed in the picking aisles between the routes of the picker vehicles traveling along the two opposing picking fronts, for the intermediate storage and/or transfer of the pick units from a picker vehicle at one side of the picking aisle to a picker vehicle at the other side of the picking aisle, and 6) a system controller comprising a control computer.
The said storage and/or supply vehicle is preferably also used to transport the units from picking aisle to picking aisle.
In a preferred development of the invention, it is provided that in each of the rack rows at least one buffer track is constructed for transferring order pallets from a picker vehicle to a storage vehicle and from there optionally to a picker vehicle of the adjacent picking aisle, and/or for transferring an order pallet from a storage vehicle to a picker vehicle. It is also possible for there to be only one picking aisle between the pallet racks. The previously described transfer and buffer locations are then situated in the pallet racks.
The system according to the invention allows single-stage picking directly onto the dispatch loading aid, namely the pallet, wherein only a single handling stage is required. Transporting of the order pallet from the start of the order up to sorting for dispatch is effected automatically by the picking system by means of buffer conveyors. The invention allows optimization of the completion time by prioritizing specific order pallets: because the invention creates the possibility of transferring the order pallets between the picker vehicles of a picking aisle via the buffer locations and the possibility of transferring the order pallets from one picking aisle to an adjacent picking aisle via the buffer tracks in the pallet racks and the respectively associated storage vehicle, order pallets may overtake one another as they run through the system. Thus, orders may be processed in a prioritized manner and passed through the installation as quickly as possible irrespective of the number of order pallets already started in the installation. It is moreover possible, by means of the buffer locations provided according to the invention, to control the work load variations of the pickers.
The system according to the invention is particularly suitable for picking articles stored on pallets from pallet racks. However, the system is also advantageously usable to pick smaller articles, which are accommodated in special storage containers and/or small load carriers KLTs or in cardboard boxes. Said storage containers may be integrated into a pallet rack either in specific storage channels, which are adapted to the dimensions of the storage containers, or by means of mobile storage channel inserts, which are inserted into the pallet channels. It is further possible to provide a separate rack module designed exclusively for picking from storage containers. The extra provision of storage space in the storage containers in addition to the pallet locations enables efficient storage and picking also of smaller articles and slow-moving articles. By virtue of the storage containers or small load carriers a reduction of the picking front and hence of the picking distance is achieved. Because of the shorter journey times a higher picking capacity and shorter order completion times are possible.
In a preferred development of the invention, it is provided that both static and dynamic picking channels are formed at the pallet racks. In the present case, the picking channels of the pallet racks are preferably designed so as to be usable both as static and as dynamic picking channels.
xe2x80x9cStatic channelsxe2x80x9d in the context of the invention are those picking channels of the pallet racks, to which articles with a high turnover are assigned within the framework of permanent pick-up locations for picking (static line-up). In the static channels there is always a plurality, preferably two to three pallets of the respective article provided one behind the other. Picking is effected from the front pallet associated with the picking front, the pallets behind are provided as stock. When the front pallet is empty, the pallet is removed by the picker and the follow-up pallets automatically roll forward by means of gravity roller conveyors. The zero passage acknowledgement of the picker triggers the provision of a new pallet from the stock area.
xe2x80x9cDynamic channelsxe2x80x9d in the context of the present invention are those picking channels of the pallet racks, in which pallets holding articles with a low turnover are lined up for picking dynamically, i.e. only when actually required, thereby reducing the size of the picking front. Specific picking channels are earmarked for dynamic line-up. When there is a request from the picking system for a dynamic article, the latter is lined up at the dynamic location and, upon a request for a new article, is removed and returned to the stock area.
Since at least some but preferably all of the picking channels are equipped so as to be usable both as static and as dynamic picking channels, the possibility arises of continuous reprofiling of the article line-up. To said end, in a preferred development of the invention it is provided that the system comprises control means for determining on the basis of records and/or prognoses and/or present orders the optimum article line-up and, in the event of a variation of definable magnitude from this, reorganizing, i.e. reprofiling the picking front. The design of the picking channels allows an automatic return of a lined-up pallet to the stock area. If a static article is to be changed, the appropriate pallets are removed from the picking channel. The picking channel may then be either statically or dynamically reassigned. Thus, a continuous reprofiling of the article line-up during operation is possible without intervention by the workforce.
Although storing of the pallets in the stock area and feeding of the pallets into the picking channels might in principle also be effected by manual stackers controllable by radio data transmission, in a preferred development of the invention it is provided that the storage vehicles take the form of automatic rack attendance units.
In the case of the present invention, stock and picking are integrated in a single system, the system according to the invention, which guarantees short servicing times. Larger quantities of stock may optionally be accommodated in a separate storage area, preferably a high-rack pallet store with a conveyor link to the system according to the invention.
The picker vehicles of the system according to the invention accommodate not only the order pallet but preferably also the picker so that the order pallets plus the picker are channelled by means of the picker vehicle successively through the picking fronts where articles for the order pallet are lined up. Automatic travel to the picking positions and automatic positioning in front of the respective picking channel is effected. As a result, waiting times of the pickers are reduced and walking distances of the pickers during picking are eliminated. As the order pallet is always carried along, there are no journey times to the order pallet.
In a preferred development of the invention it is provided that the picker vehicle carries the order pallet and the picker in a height-adjustable manner. It is particularly advantageous when the picker vehicle carries the order pallet in a height-adjustable manner relative to the picker.
In a particularly preferred development of the invention, this may be achieved in that a first lifting device with a height-adjustable picker-carrying device for the picker and a second lifting device with a height-adjustable pallet-carrying device for an order pallet are provided, wherein the picker-carrying device and the pallet-carrying device are positionable heightwise relative to the respective retrieval position independently of one another.
The picker situated on the picker-carrying device may be conveyed along the picking front by means of the vehicle. The two independently operating lifting devices of the vehicle make it possible to achieve the, in each case, ergonomically most advantageous retrieval height and delivery height for the picker-carrying device and pallet-carrying device respectively. By said means, the stresses imposed on the picker by stooping and lifting and taking down boxes from suboptimum retrieval and delivery heights are avoided. Automatic travel to the retrieval positions eliminates walking distances for the picker during picking, which leads to a substantial reduction of journey times and makes the picking process more efficient. The preferably provided computer control of the apparatus also eliminates the time taken by the picker in conventional systems to find the next retrieval position (orientation to the next bay).
In an advantageous development of the invention, the picker-carrying device comprises a cabin for the picker. Said cabin is preferably provided with a circumferential crash guard for the picker and comprises a terminal for displaying the picking positions. As an additional safety device, a dead man""s switch is advantageously provided, which may be used simultaneously to acknowledge the pick.
In a preferred development of the invention, the pallet-carrying device comprises a load-receiving means for receiving and delivering an order pallet. The load-receiving means is advantageously designed so as to enable transporting of the order pallet at right angles to the travelling direction of the vehicle.
In a particularly preferred development of the invention, the pallet-carrying device comprises a sensor device for determining the degree of charging of the order pallet, thereby enabling the height of the pallet-carrying device to be adapted to the degree of charging of the order pallet.
The picker vehicle is conveyed on rails along the picking front in a similar manner to a storage and retrieval unit and is controlled by the control computer. The vehicle is moved in longitudinal direction in accordance with the pick controller to the respective retrieval position in front of the respective active retrieval pallet and, preferably at the same time, both the picker and the order pallet are moved into an optimum vertical position. The picker may then retrieve the quantity displayed at the terminal from the retrieval pallet and transfer it to the order pallet. The picker vehicle is then steered to the next relevant retrieval position or moved to a transfer location.
In a preferred development of the invention, it is provided that the height of the picker-carrying device at the respective retrieval position is controllable on the basis of the residual stock quantity of the articles on the retrieval pallet. It is further provided that the height of the pallet-carrying device at the respective retrieval position is controllable on the basis of the degree of charging of the order pallet. In said manner it is possible to achieve an ergonomically optimum retrieval and delivery height of picker-carrying device and pallet-carrying device at any time during picking, thereby reducing the physical stress on the picker to a minimum; in particular, no strain is placed on the spinal column of the picker during the picking process.
In addition, it is advantageously provided that the height of the picker-carrying device and/or of the pallet-carrying device at the respective retrieval position is adjustable individually for each picker, i.e. in the controller the optimum access height may be geared individually to each worker. Furthermore, it is advantageously provided that the heights preset by the controller are manually correctable by the picker. In contrast, control of the travel in aisle direction is preferably effected fully automatically without the possibility of intervention by the picker.
Further advantageous features of the invention arise from the remaining sub-claims and from the following detailed description of a preferred embodiments of the invention with reference to the drawings.